[1] CERN, Div EP, CH-1211 Geneva 23, Switzerland
[2] Univ Bern, Lab Hochenergiephys, CH-3012 Bern, Switzerland
[3] Brookhaven Natl Lab, Upton, NY 11973 USA
[4] Brunel Univ, Uxbridge UB8 3PH, Middx, England
[5] Univ Geneva, Dept Radiol, CH-1211 Geneva, Switzerland
[6] Univ Glasgow, Dept Phys & Astron, Glasgow G12 8QQ, Lanark, Scotland
[7] Helsinki Univ Technol, Low Temp Lab, FI-02150 Espoo, Finland
[8] Univ Karlsruhe, IEKP, D-76128 Karlsruhe, Germany
[9] LIP, P-1000 Lisbon, Portugal
[10] Jozef Stefan Inst, Exp Particle Phys Dept, Ljubljana 1001, Slovenia
[11] Tech Univ Munich, Dept Phys E18, D-85748 Garching, Germany
[12] Univ Frederico II Napoli, Dipartimento Fis, Naples, Italy
[13] Ist Nazl Fis Nucl, I-80125 Naples, Italy
[14] Russian Acad Sci, AF Ioffe Physicotech Inst, St Petersburg 194021, Russia